From owner-freebsd-questions@freebsd.org Mon Oct 22 15:53:25 2018 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 935F310364FC for ; Mon, 22 Oct 2018 15:53:25 +0000 (UTC) (envelope-from doug@safeport.com) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id 2C4ED811A0 for ; Mon, 22 Oct 2018 15:53:25 +0000 (UTC) (envelope-from doug@safeport.com) Received: by mailman.ysv.freebsd.org (Postfix) id E567D10364F9; Mon, 22 Oct 2018 15:53:24 +0000 (UTC) Delivered-To: questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id C2FC610364F7 for ; Mon, 22 Oct 2018 15:53:24 +0000 (UTC) (envelope-from doug@safeport.com) Received: from cyrus.watson.org (cyrus.watson.org [204.107.128.30]) by mx1.freebsd.org (Postfix) with ESMTP id 6FE5E8119E for ; Mon, 22 Oct 2018 15:53:24 +0000 (UTC) (envelope-from doug@safeport.com) Received: from fledge.watson.org (fledge.watson.org [198.74.231.63]) by cyrus.watson.org (Postfix) with ESMTPS id AD0479F49D; Mon, 22 Oct 2018 15:53:18 +0000 (UTC) Received: from fledge.watson.org (doug@localhost.watson.org [127.0.0.1]) by fledge.watson.org (8.15.2/8.15.2) with ESMTP id w9MFrIwP056197; Mon, 22 Oct 2018 11:53:18 -0400 (EDT) (envelope-from doug@safeport.com) Received: from localhost (doug@localhost) by fledge.watson.org (8.15.2/8.15.2/Submit) with ESMTP id w9MFrHUf056193; Mon, 22 Oct 2018 11:53:17 -0400 (EDT) (envelope-from doug@safeport.com) X-Authentication-Warning: fledge.watson.org: doug owned process doing -bs Date: Mon, 22 Oct 2018 11:53:17 -0400 (EDT) From: doug@safeport.com X-X-Sender: doug@fledge.watson.org Reply-To: doug@fledge.watson.org To: Ian Smith cc: Polytropon , questions@freebsd.org Subject: re: FreeBSD boot manager customization for single-disk multiboot (4 x DOS) In-Reply-To: <50139023-EF23-4464-8E99-4958CB3A3044@exemail.com.au> Message-ID: References: <50139023-EF23-4464-8E99-4958CB3A3044@exemail.com.au> User-Agent: Alpine 2.20 (BSF 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3 (fledge.watson.org [127.0.0.1]); Mon, 22 Oct 2018 11:53:18 -0400 (EDT) X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 22 Oct 2018 15:53:25 -0000 On Mon, 15 Oct 2018, Ian Smith wrote: > Hi there heroic wanderer, it's been a while. > > I only rarely read questions@ these days, from the archives, but this one I thought maybe I could help with. I'm in a care situation, tapping this out in K9mail on a small phone, so will try to be concise. > > I've read the thread. Manish is trying to help but his DOS familiarity doesn?t go back far enough. I started at 2 and used 3.3 (with Desqview), later 5.0 for years running Fidonet mailer, BBS, message editor, DOS command space and other tasks in 6 MiB RAM .. so had to learn how to really squeeze things in - as did you, I gather. > > Correct, you cannot boot DOS from a non-primary partition. Maybe you could use GRUB, it installs after the MBR on track 0 side 0 so shouldn't get in the way. > > I dont think you need to install linux to install GRUB? That said, I don't use it myself. To add linux to the 4-DOS mix would need an extended partition, leaving only 3 primaries for 3 x DOS. Same deal with OS/2, with its great boot manager. > > boot0.s MBR code is VERY tight with about ZERO free space as I recall .. however there's code there - still was at 9.x I think - for a 1? (2 sector) version written by the same author (Robert Nordier IIRC, I don't have a system to hand). That should have plenty of room for more lavish labels, and may in fact include such code? If you have a spare system you could assemble that and test. > > Of course you'll have a backup MBR (directed more at other readers :) > > One thing to watch is that esp. earlier versions of DOS may want to use the first slice explicitly? I'm not sure, but I'd start with earliest versions first, and test each as you go. > > Please CC me on any replies. > > cheers, Ian I wrote DOS MultiBoot for DOS and OS/2 many moons ago. My memory is with DOS 4 the rules about where the 2nd level boot code went were relaxed. The boot code invooked from the BIOS had to be in sector 0 of the first track on the disk. In those days you had the rest of the track to "play" with. I do not know if any of that historical information helps but I am 99% sure my memory is accurate. If track 0 is still available perhaps grub could be installed there? Booting passed me by a couple of decades ago. I hope the history helps. Do post to let us know the outcome.